The tryptophanyl-tRNA synthetase of Escherichia coli will be specifically cleaved to produce peptide fragments, which will be isolated and sequenced. The overall goal is determination of the complete primary sequence of the enzyme. In addition, we shall continue efforts to crystallize the enzyme in a form suitable for x-ray crystallography. BIBLIOGRAPHIC REFERENCES: G.V. Kuehl, M. Lee, and K.H. Muench. "Tryptophanyl Transfer Ribonucleic Acid Synthetase of Escherichia Coli. Character of Required Thiol Group and Structure of Thiol Peptides." J. Biol. Chem. 251, 3254-3260, 1976. M.S. Lipscomb, M. Lee, and K.H. Lipscomb, M. Lee, and K.H. Muench, "Human Tryptophanyl Transfer Ribonucleic Acid Synthetase. Composition, Function of Thiol Groups, and Structure of Thiol Peptides." J. Biol. Chem. 251, 3261-3268, 1976.